The invention is generally in the field of hand tools and levelling devices, and is more particularly concerned with the relatively precise marking of reference lines at any angle over a generally flat surface. The compactness, portability and relative accuracy of the invention render it of great usefulness to the professional builder and carpenter, while the ease of use and lack of skill needed in the operation of the invention make it of particular use to the DIY enthusiast.
There have been a number of surveying and carpentry tools employing the use of beams of light generated by lasers. Most of these have concerned themselves with producing a horizontal plane of light from a floor or tripod-mounted unit and have addressed the needs of large constructional and civil engineering works. Early devices were relatively cumbersome, required precise manual levelling and utilised helium-neon lasers which required mains electricity supplies.
According to the present invention, however, a laser light referencing tool comprises laser means for emitting a visible laser beam, portable power means for powering the laser means, and gravity-responsive directional means for establishing a datum direction for the laser means.
The gravity-responsive means may include one or more batteries and/or may include one or more other weights.
Preferably, control means is provided for enabling the laser means to be moved in a controlled manner so that the visible laser beam is emitted in a controlled direction relative to said datum direction.
Said control means may be based on friction and the friction may be adjustablexe2x80x94said control means may be such as to allow the laser means to be fully rotatable, rather than merely pivotable, to allow the laser means to be set at any selected angle within 360xc2x0.
It will thus be appreciated that the present invention can provide a hand-portable tool capable of producing a reference line at any angle in any single plane. When used as a levelling device against a generally vertical surface, a reference line will be projected over that surface generally at the horizontal or at any preset angle away from the horizontal, despite the angle at which the tool is held against the substantially vertical surface, and without the need for any pre-levelling of the instrument. It will also be appreciated that the tool of the present invention can be rugged and lightweight as well as compact and portable.
Preferably, the present invention is a small rugged referencing tool which is compact and light enough to be easily held in the palm of one hand, leaving the other hand free to mark the generally vertical surface over which the reference line is projected by the tool. The operator may mark such a line over as wide a span as his or her arms will allow. When placed against the generally vertical surface, the case of the tool or any attached handle may be held at any angle, and in either hand without altering the angle of the displayed reference line. The tool may also be placed on any convenient generally horizontal surface, or on a suitable stand or tripod, allowing a completely hands-free operation over the tool""s range. This range is dependent only on the power of the laser means employed, and the quality of the optical elements used. Means are also disclosed as to how the tool may be fixed to the generally vertical surface being referenced, allowing similar hands-free operation.
Attachments are described which enhance the tool""s versatility, allowing it to be used to provide a visible reference line as an extension to a surface, (either substantially horizontal/vertical, at any preset angle away from the horizontal or along the same plane as the surface of origin), and as a tool for providing a visible reference line at any angle over any plane.
A means of overcoming the obscuring effect of strong ambient light, such as direct sunlight, is also disclosed.
Other arrangements are described which can provide a pair of reference points at the generally horizontal, or at any angle away from the generally horizontal, across open space.
A first embodiment has a case containing batteries which supply power to a laser diode contained in a first axially pivoted cylindrical housing. This cylindrical housing and its contents are substantially in balance around its axis. Any imbalance in this housing may be rectified by an adjustable weight in the form of a fine balancing slug threaded into a balancing weight set in the housing. Via optical means including a collimating lens and a line producing lens, the laser diode produces a beam of light, divergent in a single plane only, along the radial line of the cylindrical housing. Thus, when placed close to and generally parallel to a generally vertical, generally flat surface, a horizontally divergent beam will strike the surface at an oblique angle, and a thin line of light of generally uniform thickness will be projected over that surface.
Axially attached to the laser diode housing is a second cylindrical housing containing an eccentric weight. The effect of gravity on this eccentric weight makes a zero to one hundred and eighty degree line marked on the outside of the second cylindrical housing align generally with the horizontal. The alignment of the second cylindrical housing may be finely adjusted by a balancing slug threaded into the eccentric weight. When the two cylindrical housings are rotated relative to each other, friction between the two housings maintains the angle of rotation. As the cylindrical housing containing the laser diode and its associated circuitry is generally in balance around its axis, whatever the preset angle of rotation of the laser diode housing, no significant deviation will be experienced by the cylindrical housing containing the eccentric weight. Thus, the beam of visible light output by the laser diode may be preset to the horizontal or any angle away from the horizontal.
Adjustable point bearings on the axis of the cylindrical laser diode/weight assembly not only allow the free rotation of that assembly, but, being made of an electrically conductive material, supply electrical power from the batteries in the case of the tool to the laser diode assembly, without the need for connecting wires which would impede the free rotation of the assembly.
A switch can be included in the tool to interrupt the electrical supply, and an electronic timing circuit can also be included to provide an automatic shut-down of power after a predetermined time in order that battery life may be conserved. A visible indicator of the laser diode""s operation, such as. a low-power flashing LED might also be used. A mechanical locking device can allow the cylindrical housing containing the eccentric weight to be rendered immobile relative to the case of the tool, while still allowing the cylindrical housing containing the laser diode assembly to be rotated. Thus, a line of light at a preset angle relative to the outside surface of the case of the tool may be projected over any generally flat surface against which, or on which the tool is placed.
A second embodiment utilises a pair of laser diodes mounted back to back in a cylindrical housing. Two beams, axially in general alignment are projected from the housing via optical means including collimating lenses and plain lenses. This cylindrical housing is connected to a cylindrical housing containing an eccentric weight as detailed above, and may be similarly rotated relative to it. With the tool held generally vertically, two beams of substantially non-divergent laser light are projected radially at the horizontal, or at a preset angle away from the horizontal. Two points are illuminated by the beams of light, the angle between them relative to the horizontal being determined by the angle of rotation of one cylindrical housing relative to the other.
A third embodiment has a single laser diode mounted radially in, and pointing to the centre of, a cylindrical housing. At the centre of this housing is fixed a right-angled mirror. This mirror splits the beam of laser light and projects two beams radially from the housing in a similar manner to that detailed above.
A fourth embodiment has a laser diode, associated circuitry, collimating lens, line generating lens, balancing weight and fine balancing slug mounted in a cylindrical housing as in the first embodiment. The cylindrical housing is axially attached via studs to one end of an elongate pendular assembly including two composite strips of electrically conducting and non-conducting material. Friction prevents the cylindrical housing from rotating freely, but this friction may be overcome by finger pressure. Set into the other end of these strips are metal discs with conical depressions. Threaded pointed screws, attached to a case of the tool, engage in these depressions. Electrically conducting strips connect these screws with wires which in turn connect via a switch to batteries. Electrical power is thus supplied to the laser diode via the pointed screws, from which the composite strips and cylindrical housing depend. Mounted in the cylindrical housing are two identical weights. The cylindrical housing is thus generally in balance around its axis. Markings on the surface of the cylindrical housing allow the housing to be rotated to a preset angle relative to the composite strips and hence relative to the generally vertical. Thus a line of light at a preset angle may be projected over a generally vertical, generally flat surface as detailed in the first embodiment. The other end of the elongate pendular assembly is rotatably mounted to a holding case.
A fifth embodiment has a laser diode, associated circuitry, collimating lens and line generating lens mounted in a cylindrical housing. The cylindrical housing is axially attached via studs to one end of an elongate pendular assembly in the form of a battery case. Friction prevents the cylindrical housing from rotating freely, but this friction may be overcome by finger pressure. Said one end of the elongate pendular assembly is also rotatably mounted to a holding case, the battery case/laser diode housing assembly being pivotable relative to the holding case by means of pointed threaded screws and metal rings with conical depressions as described in the first embodiment. The battery case of this fifth embodiment performs the function of the axially connected eccentric weight housing of the first embodiment. Gravity acts on it so that it hangs generally vertically from the pointed screw bearings. When the cylindrical housing is rotated to a preset angle relative to the battery case, a line of light at a preset angle may be projected over a generally vertical, generally flat surface as detailed in the first embodiment.
A sixth embodiment, which is the currently preferred embodiment, is similar to the first embodiment in including first and second cylindrical housings whose relative rotational positions are controlled by friction. However, the gravity-responsive directional means now comprises the portable power means (one or more batteries). Said first and second cylindrical housings are rotatably mounted at one end of a holding case, and are rotatably mounted to the holding case by means of a magnetised suspension assembly. Access to said first and second cylindrical housings is via a curved clear window which is a friction fit with the holding case. The other end of the holding case is provided with a plurality of translucent windows carrying parallel markings. There may be three translucent windows arranged respectively at said other end and at two sides of the holding case.
Individual features of the various embodiments may be combined differently.